The present invention relates to polyhydric phenol compounds and epoxy resins obtained by glycidyl etherification thereof, which are suitable for use in various kinds of materials of plastics (polycarbonate, PEEK, PPO, polysulfone, etc.); materials of thermosetting resins (epoxy resin, cyanate resin, acrylate resin, etc.); antioxidants; insulating materials for electric and electronic parts including highly reliable sealing compounds for semiconductors; various composite materials including laminated sheets (printed-wiring boards) and CFRP (carbon fiber-reinforced plastics); components of adhesive compositions, coating compositions and molding compositions; as well as various industrial intermediates.
Polyhydric phenol compounds have actually a wide variety of applications in the fields of thermoplastic materials, thermosetting resin materials, insulating materials for electric and electronic parts, structural materials, components of adhesive compositions and coating compositions, as well as antioxidants.
In recent years, however, polyhydric phenol compounds have been applied to a wide variety of uses and requested to satisfy more diversified property requirements, which conventional compounds such as bisphenol A, bisphenol F, phenolic novolak and cresol novolak would fail to meet. For the purpose of satisfying these new property requirements, many polyhydric phenol compounds have been synthesized. In the fields of electric and electronic parts, in particular, there is a need for curable resin compositions and cured products thereof having a low viscosity, a low hygroscopicity and high adhesive properties, but such need remains unsatisfied.
On the other hand, epoxy resins obtained by glycidyl etherification of polyhydric phenol compounds, by virtue of having good working properties of their own as well as by virtue of having excellent electrical properties, a high heat resistance, good adhesive properties and a high moisture resistance (water resistance) in the form of cured products thereof, are widely used in the fields of electric and electronic parts, structural materials, adhesive compositions, coating compositions and the like.
With the recent development of electrics and electronics, however, these fields are in need of resins having more improved properties including a higher purity, a higher moisture resistance, better adhesive properties and a lower viscosity permitting a high packing density of filler. Also, lightweight materials having excellent mechanical and physical properties are needed as structural materials for use in aerospace industries and equipments for leisure time amusement and sports. In an attempt to meet these requirements, many improvements of epoxy resins and epoxy-containing resin compositions have been proposed, but these requirements still remain unsatisfied.
The present inventors, with the intention of solving the problems set forth above, have eagerly studied on novel polyhydric phenol compounds and epoxy resins obtained by glycidyl etherification thereof and accomplished the present invention.
More specifically, the present invention relates to:
(1) a polyhydric phenol compound represented by the formula (1): 
xe2x80x83wherein, X represents an oxygen or sulfur atom; Q represents a hydrogen atom or a C1-C5 alkyl group; R represents a hydrogen atom, a C1-C10 hydrocarbon group, an alkoxy group or a halogen atom; i is an integer of 1 to 6; j is an integer of 1 to 3; k is an integer of 1 to 5; and y is an integer of 1 to 2; n is an average number and represents a real number of 1 to 15;
(2) the polyhydric phenol compound as defined in the above item (1), characterized in that it is represented by the formula (2): 
xe2x80x83wherein X, Q, R and j are of the same meanings as defined in the formula (1); and h is an integer of 1 to 4;
(3) the polyhydric phenol compound as defined in the above item (1) or (2), wherein X in the formula (1) represents an oxygen atom;
(4) the polyhydric phenol compound of any one of the above items (1) to (3), wherein n represents a number of not less than 1.5 and less than 10;
(5) a process for producing a polyhydric phenol compound comprising condensing a phenol with a compound of the formula (a): 
xe2x80x83wherein X, Q and j are of the same meanings as defined in the formula (1), in the presence of a basic catalyst;
(6) the process as defined in the above item (5), wherein the phenol is 2, 6-xylenol;
(7) the process as defined in the above item (5), wherein the phenol is 2, 5-dialkylphenol;
(8) the process as defined in any one of the above items (5) to (7), wherein the basic catalyst is at least one compound selected from the group consisting of alkaline metal oxides, alkaline earth metal oxides, alkaline metal alkoxides and alkaline earth metal alkoxides;
(9) an epoxy resin represented by the formula (3): 
xe2x80x83wherein G represents a glycidyl group and R, Q, X, n, y, i, j and k are of the same meanings as defined in the formula be (1);
(10) an epoxy resin represented by the formula (4): 
xe2x80x83wherein G, R, Q, X and j are of the same meanings as defined in the formula (3); m is an average value and represents a real number of 0 to 20; and h represents an integer of 1 to 4;
(11) a thermosetting resin composition containing a polyhydric phenol compound as defined in anyone of the above items (1) to (3) and/or an epoxy resin as defined in the above item (9) or (10);
(12) a cured product obtained by curing the thermosetting resin composition of the above item (11);
(13) a semiconductor device fabricated by incorporating the thermosetting resin composition as defined in the above item (11);
(14) a thermoplastic material fabricated by starting with a polyhydric phenol compound as defined in any one of the above items (1) to (3).